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From 3cce747e84f3e12dc20368a85be694828e8e6eb7 Mon Sep 17 00:00:00 2001
From: Sami Tolvanen <samitolvanen@google.com>
Date: Mon, 13 Apr 2020 16:10:13 -0700
Subject: [PATCH 07/24] kbuild: lto: postpone objtool
With LTO, LLVM bitcode won't be compiled into native code until
modpost_link, or modfinal for modules. This change postpones calls
to objtool until after these steps.
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
---
scripts/Makefile.build | 2 ++
scripts/Makefile.modfinal | 15 +++++++++++++++
scripts/link-vmlinux.sh | 9 +++++++++
3 files changed, 26 insertions(+)
diff --git a/scripts/Makefile.build b/scripts/Makefile.build
index 64e99f4baa5b..82977350f5a6 100644
--- a/scripts/Makefile.build
+++ b/scripts/Makefile.build
@@ -226,6 +226,7 @@ endif # CC_USING_PATCHABLE_FUNCTION_ENTRY
endif # CONFIG_FTRACE_MCOUNT_RECORD
ifdef CONFIG_STACK_VALIDATION
+ifndef CONFIG_LTO_CLANG
ifneq ($(SKIP_STACK_VALIDATION),1)
__objtool_obj := $(objtree)/tools/objtool/objtool
@@ -258,6 +259,7 @@ objtool_obj = $(if $(patsubst y%,, \
$(__objtool_obj))
endif # SKIP_STACK_VALIDATION
+endif # CONFIG_LTO_CLANG
endif # CONFIG_STACK_VALIDATION
# Rebuild all objects when objtool changes, or is enabled/disabled.
diff --git a/scripts/Makefile.modfinal b/scripts/Makefile.modfinal
index d168f0cfe67c..9f1df2f1fab5 100644
--- a/scripts/Makefile.modfinal
+++ b/scripts/Makefile.modfinal
@@ -48,6 +48,21 @@ endif # CC_USING_PATCHABLE_FUNCTION_ENTRY
endif # CC_USING_RECORD_MCOUNT
endif # CONFIG_FTRACE_MCOUNT_RECORD
+ifdef CONFIG_STACK_VALIDATION
+ifneq ($(SKIP_STACK_VALIDATION),1)
+cmd_ld_ko_o += \
+ $(objtree)/tools/objtool/objtool \
+ $(if $(CONFIG_UNWINDER_ORC),orc generate,check) \
+ --module \
+ $(if $(CONFIG_FRAME_POINTER),,--no-fp) \
+ $(if $(CONFIG_GCOV_KERNEL),--no-unreachable,) \
+ $(if $(CONFIG_RETPOLINE),--retpoline,) \
+ $(if $(CONFIG_X86_SMAP),--uaccess,) \
+ $(@:.ko=$(prelink-ext).o);
+
+endif # SKIP_STACK_VALIDATION
+endif # CONFIG_STACK_VALIDATION
+
endif # CONFIG_LTO_CLANG
quiet_cmd_ld_ko_o = LD [M] $@
diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh
index c5715608fe63..7e9de077ee7f 100755
--- a/scripts/link-vmlinux.sh
+++ b/scripts/link-vmlinux.sh
@@ -89,8 +89,17 @@ objtool_link()
{
local objtoolopt;
+ if [ "${CONFIG_LTO_CLANG} ${CONFIG_STACK_VALIDATION}" = "y y" ]; then
+ # Don't perform vmlinux validation unless explicitly requested,
+ # but run objtool on vmlinux.o now that we have an object file.
+ objtoolopt="check"
+ fi
+
if [ -n "${CONFIG_VMLINUX_VALIDATION}" ]; then
objtoolopt="check --vmlinux"
+ fi
+
+ if [ -n "${objtoolopt}" ]; then
if [ -z "${CONFIG_FRAME_POINTER}" ]; then
objtoolopt="${objtoolopt} --no-fp"
fi
--
2.28.0
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